1. Field of the Invention
This invention pertains to apparatus for conveying small fungible products for optical sorting and more specifically for singulating such products as broad beans, almonds and the like that often do not singulate or separate from each other when conveyed in conventional fashion.
2. Description of the prior art
Small fungible products are conventionally inspected and sorted by optical viewing means by being conveyed down an appropriate chute or slide past the optical viewing station. Conventional sorting machine electronics operate on the principle that one product at a time passes the viewing station even though a stream of such products occurs so fast that the naked eye cannot separate one conveyed product from another. A prior art slide conveyor for conveying such items as coffee beans or other such products, both agricultural and non-agricultural, has a U-shaped cross section with a relatively large bottom radius. That is, the sides of the slide slope inwardly toward each other at an acute angle, but at an angle that is larger than the largest radius of the products being conveyed. A bean, for example, is generally spherical and is shaped to have a long axis and a short axis, the short axis generally subtending an arc that has a smaller radius than the arc generally subtended by the long axis. The U-shaped bottom of a conventional conveyor has a radius that is larger than even the products large radius.
The conventional conveyor is positioned at an angle to a level floor in excess of 45 degrees. The entrance to the slide conveyor is conventionally fed by a hopper-and vibratory feeder that dumps a relatively large quantity onto the slide at one time. As the products slide or roll down the slide, they gradually unstack themselves so that by the time they pass by the viewing station of the sorter, the products are no longer overlapping each other. This permits the electronics of the machine to consider each viewed object on its own merits. Thus, if a viewed product is too short, too long, has too large a dark spot, or too large a light spot or is too light or too dark overall, the reject mechanism for separating the "substandard" or "nonstandard" product, usually an air jet, is only actuated to remove the nonstandard product and not others. By contrast, a slide that does not adequately singulate in the fashion just described can produce a bunching of products that will be detected as too long for a single product and, therefore, cause a rejection that never should have occurred at all. This bunching of product can also "hide" defects from the optics, and cause the machine to accept "bad" product.
It should be noted that a conventional slide of the type just described does not particularly orient the spherical shaped products assumed above as they emerge or pass from the exit of the slide. That is, if the products tend to be a little longer in one dimension than another, some will slide off or roll off one way and others will slide off or roll off oriented differently. That is, there is no uniform or consistent orientation of the products even though they are singulated. In many applications, this does not make any difference, but in some applications where the products are more disc shaped than spherical shaped, it very well may be important to optical viewing.
It should also be noted that products that are more disc-shaped, with or without a pointed end, than spherical shaped do not consistently singulate in the type of slide just described. For example, broad beans are substantially disc shaped, somewhat like a miniature discuss wherein the sides are slightly convex although referred to loosely as being flat. The edges have a small radius, actually much smaller than a spherical product of the type discussed above. Almonds are also somewhat disc shaped in the same manner as broad beans, however, almonds also have a pointed end. When broad beans, almonds, or similar "flat" sided disc-like products are conveyed down a conveyor of the conventional type previously described, sometimes two or three of such products will wedge together in the U-shaped bottom. Other times, one such product will straddle the bottom angle and skid along the sides with or without other of such products. When either of these randomly occurring events happens, then the slide does not function to singulate the products and the products exiting will often be bunched together. As described above, bunched products can result in erroneous rejection or sorting of individually standard-sized products. Moreover, products that exit after straddling the bottom can be viewed as substandard in width compared with products that are oriented to be approximately in a plane bisecting the bottom angle of the slide.
Therefore, it is a feature of the present invention to provide an improved slide for sorting machines that dependably singulates and orients products that are more disc-like than spherical-like.
It is another feature of the present invention to provide an improved slide for sorting machines that dependably presents the "flat" side of disc-like products for optical view sorting, regardless of whether the products also have a pointed end.
It is still another feature of the present invention to provide an improved slide for sorting machines of the type described above without resorting to auxiliary moving parts.